 /* crypto/bn/bn_add.c */

 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 * 

 * This library is free for commercial and non-commercial use as CrLONG32 as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 * 

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 * 

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from 

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 * 

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 * 

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */



#include "crypto/CrBNConfig.h"

#ifdef _BN_ADD_C



//#include <stdio.h>

//#include "crypto/cryptlib.h"

#include "crypto/CrBN.h"

#include "crypto/CrBNLcl.h"





 /* r can == a or b */

CrINT32 BN_add(BIGNUM *r, BIGNUM *a, BIGNUM *b)

{

	CrUINT32 i;

	BIGNUM* tmp;



	 /*  a +  b	a+b

	 *  a + -b	a-b

	 * -a +  b	b-a

	 * -a + -b	-(a+b)

	 */

	if (a->neg ^ b->neg)

	{

		 /* only one is negative */

		if (a->neg)

		{ tmp=a; a=b; b=tmp; }



		 /* we are now a - b */



		if (BN_ucmp(a,b) < 0)

		{

			if (bn_wexpand(r,b->top) == NULL) return(0);

			bn_qsub(r,b,a);

			r->neg=1;

		}

		else

		{

			if (bn_wexpand(r,a->top) == NULL) return(0);

			bn_qsub(r,a,b);

			r->neg=0;

		}

		return(1);

	}



	if (a->neg)  /* both are neg */

		r->neg=1;

	else

		r->neg=0;



	i=(a->top > b->top);



	if (i)

	{

		if (bn_wexpand(r,a->top+1) == NULL) return(0);

		bn_qadd(r,a,b);

	}

	else

	{

		if (bn_wexpand(r,b->top+1) == NULL) return(0);

		bn_qadd(r,b,a);

	}

	return(1);

}



 /* unsigned add of b to a, r must be large enough */

void

bn_qadd(BIGNUM *r, BIGNUM *a, BIGNUM *b)

{

	register CrINT32 i;

	CrINT32 max,min;

	BN_ULONG *ap,*bp,*rp,carry,t1;



	// inserted by dongjin(2000/7/20)

	if(b->top==0) 

	{

		for (i=0; i<a->top; i++)

			r->d[i] = a->d[i];

		r->top = a->top;

		return;

	}



	max=a->top;

	min=b->top;

	r->top=max;



	ap=a->d;

	bp=b->d;

	rp=r->d;

	carry=0;



	carry=bn_add_words(rp,ap,bp,min);

	rp+=min;

	ap+=min;

	bp+=min;

	i=min;



	if (carry)

	{

		while (i < max)

		{

			i++;

			t1= *(ap++);

			if ((*(rp++)=(t1+1)&BN_MASK2) >= t1)

			{

				carry=0;

				break;

			}

		}

		if ((i >= max) && carry)

		{

			*(rp++)=1;

			r->top++;

		}

	}

	for (; i<max; i++)

		*(rp++)= *(ap++);

	 /* SMemcpy(rp,ap,sizeof(*ap)*(max-i));*/

}



#endif //ifdef _BN_ADD_C


